1. Field of the Invention
This invention relates generally to a catheter, used to achieve stable selective catheterization of a vessel, that will function as a guiding catheter to permit the coaxial passage of other catheters and devices including Percutaneous Transluminal Coronary Angioplasty (PTCA) and non-coronary Percutaneous Transluminal Angioplasty (PTA) catheters through it into the catheterized vessel.
2. Description of the Prior Art
The design of a practical catheter system equipped with a balloon at its distal end for use in dilation of narrowed vascular structures is generally credited to Dr. Andreas Gruntzig although several balloon and non-balloon dilation catheters had been designed and used prior to Dr. Gruntzig's device. When the balloon portion of the catheter is inflated in a lesion such as a narrowed region of a vascular structure, a controlled injury is produced which increases the overall cross-sectional area of that vascular structure. This process is called Percutaneous Transluminal Coronary Angioplasty (PTCA) in the case of coronary arteries and Percutaneous Transluminal Angioplasty (PTA) in the case of non-coronary vascular structures (including vascular structures other than blood vessels). Although usually introduced into the body via a skin puncture (hence "percutaneous"), these catheters may also be introduced into the body via a surgical procedure appropriate to the area to which access is desired.
Balloon dilation catheters are made of many different materials and are made in many different sizes and shapes including different balloon lengths and diameters.
Some PTA catheters are made of sufficiently strong material that they can be used to catheterize a vessel without the use of any external support. Such catheters are advanced in vessels using only a coaxial inner guide wire support which is advanced into the vessel ahead of the catheter and stabilized in a manner that will permit the catheter to be slid into a desired location over the stabilized guide wire. However, small caliber PTA catheters and most PTCA catheters are so flexible that they require the use of a coaxial guiding catheter for external support. The distal end of the guiding catheter is placed in the vessel (or a vessel leading to the vessel) into which it is desired to place the PTCA/PTA catheter and the PTCA/PTA catheter advanced through this guiding catheter to the desired location (usually with the aid of a coaxial guide wire passed through the PTCA/PTA catheter).
One of the principal causes of technical failure in the performance of PTCA/PTA procedures is the inability to obtain a sufficiently stable guiding catheter position that will permit placement of the PTCA/PTA dilation catheter at the lesion site for the proposed PTCA/PTA procedure. When the force required to advance the PTCA/PTA dilation catheter through the vessel becomes greater than the forces which tend to keep the distal end of the guiding catheter in the vessel ostium, further efforts to advance the PTCA/PTA dilation catheter result in transmission of force to the guiding catheter in a direction such that the distal end of the guiding catheter is pushed backwards out of the vessel ostium and no further advancement of the PTCA/PTA dilation catheter occurs. This problem becomes particularly significant as the length and/or severity of narrowing of the lesion increase since these factors increase the frictional forces which tend to resist passage of the PTCA/PTA dilation catheter through the area of the lesion. Tortuosity of the PTCA/PTA target vessel or the vessels that must be traversed by the PTCA/PTA dilation catheter in order to reach the lesion site also tends to increase frictional resistance to the advancement of the PTCA/PTA dilation catheter. These problems become especially significant when the width and/or orientation of the aorta in the region of the vessel ostium or the course of the proximal vessel segment that must be traversed in order to reach the lesion site are such that catheterization with standard prior art PTCA/PTA guiding catheters proves difficult or unstable. This instability manifests itself as either simple inability to maintain the desired position of the PTCA/PTA guiding catheter long enough to accomplish the intended procedure or, more often, dislodging of the guiding catheter from the vessel ostium in the course of attempting to advance the PTCA/PTA dilation catheter as described above. This dislodging is commonly referred to as the "backing out" phenomenon.
When guiding catheters are used for the passage of devices other than angioplasty catheters, similar stability problems are encountered including the "backing out" phenomenon.
Current prior art guiding catheters do not provide a solution for these noted problems.
Prior art guiding catheters known to the Applicant and described above, are simple catheters having no provision to stabilize the guiding catheter at the ostium of the target vessel. In fact, the current problems noted above only arose with the introduction and use of the existing prior art guiding catheters.
The present invention discloses a solution to the problems noted above to be common with the prior art devices.